Measurements in N2CH4(C2H2) discharges of reaction rates and thermochemical constants for Titan atmosphere study

The kinetic reactions in N2xCH4(C2H2) gas discharges with x less than 1% have been studied by emission spectroscopy in the afterglow of D.C. discharges and by mass spectroscopy from radiolysis ionization using α particles. The pressure range is from several Torr to 100 Torr. end of N2 D.C. discharges at room temperature, for a residence time of about 10−2 s, the dominant active species are the N atoms with density of 1014–1015 cm−3 for N2 density of about 1017 cm−3 (3 Torr), the N2(X, V) vibrational molecules with for example [N2(X, V = 10)] ∼ 1014 cm−3 and the electronic metastable molecules N2(A3Σu+) with a density of 1012 cm−3. In such conditions, the following kinetic reactions have been studied: N2(A)+N2(A)→N2(C, B, V′)+N2(X). N2(A)+N2(X, V > 5) →N2(X)+N2(B, V′) in pure N2 post-discharges and N2(A)+CH4→productsC+N+M2→CN(B, V′+M2N2(X, V > 4)+CN→N2(X)+CN(B, A, V′). in N2-1‰ CH4 post-discharges. ustering reactions of N2-(1–5%)CH4(C2H2) gas mixtures after radiolysis ionization have been studied for the H2CN+ ·nN2 ions and the equilibrium constants have been determined in the temperature range T = 140–300 K.